Ultrahigh vacuum scanning tunneling microscopy/magnickel oxide filmsnetic force microscopy study of ultrathin iron films grown on polycrystalline nickel oxide films
Ultrahigh vacuum scanning tunneling microscopy/magnickel oxide filmsnetic force microscopy study of ultrathin iron films grown on polycrystalline nickel oxide films
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Date
2002-05-15
Authors
Dreyer, M.
Hwang, D. G.
Gomez, R. D.
Advisor
Citation
M. Dreyer, D. G. Hwang, and R. D. Gomez, "Ultrahigh vacuum scanning tunneling microscopy/magnetic force microscopy study of ultrathin iron films grown on polycrystalline nickel oxide films", J. Appl. Phys. 91, 8138 (2002)
DRUM DOI
Abstract
The thickness dependence of the topographic and magnetic structure of ultrathin Fe films grown on
polycrystalline NiO films under ultrahigh vacuum ~UHV! conditions was studied to investigate the
growth mechanism of the ferromagnetic film and the corresponding magnetic interaction with the
antiferromagnetic substrate. Externally prepared NiO films of 60 nm thickness were cleaned by
heating in UHV. Ultrathin layers of Fe in the range of 1–27 nm were deposited on top of the NiO
film and were analyzed at specific coverages. Iron grows as a polycrystalline film with the grains
increasing in size with the thickness. The contours of the underlying NiO crystallites were evident
at low coverages but gradually disappeared as the Fe grains coalesced at thicker coverages.
Magnetic force microscopy images of the 1 nm thick film show randomly oriented magnetic grains
with an average domain size of 30 nm. With an increase in film thickness the size of the domains
grows to about 200 nm at 15 nm of iron. At a film thickness of 19 nm cross-tie domain walls become
visible, indicating the crossover of some parts of the film from random magnetic grains into
continuous domains with in-plane magnetization. A further increase in the film thickness leads to
larger in-plane domains, while there are some areas with localized grains on the surface.